Cell Selection Method, User Equipment and Storage Medium

This application is a continuation of International Application No. PCT/CN2023/118556 filed Sep. 13, 2023, which claims priority to Chinese Patent Application No. 202211686431.9 filed Dec. 27, 2022, and the entire contents of which are incorporated herein by reference.

The present disclosure relates to the field of communication technology, and particularly to a cell selection method, user equipment and a storage medium.

In the 3rd Generation Partnership Project (3GPP) protocol, when user equipment performs cell selection, it would camp on a cell as long as the S criterion is met. The user equipment might camp on a cell with poor network signals, resulting in a weak signal for the user equipment.

Embodiments of the present disclosure provide a cell selection method, user equipment and a non-transitory computer-readable storage medium.

In a first aspect, the embodiments of the present disclosure provide a cell selection method, and the method includes: measuring a signal quality of a target cell; and in response to the signal quality of the target cell being less than a target threshold, performing cell selection based on a first cell selection criteria, where a minimum access level parameter of the first cell selection criteria is greater than a minimum access level parameter of an initial cell selection criteria.

In a second aspect, the embodiments of the present disclosure provide user equipment including a processor and a memory. The memory is configured to store a computer program including program instructions. The processor is configured to call the program instructions to execute the operations in the first aspect of the embodiments of the present disclosure.

In a third aspect, the embodiments of the present disclosure provide a non-transitory computer-readable storage medium storing a computer program. The computer program causes a computer to execute part or all of the operations described in the first aspect of the embodiments of the present disclosure.

Terms “first”, “second”, and “third” etc. in the embodiments of the specification, the claims and the drawings of the present disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, terms “comprise”, “include” and “have” and any variations thereof, are intended to cover non-exclusive inclusion. For example, a method, system, product, or device including a series of operations or elements is not necessarily limited to those operations or elements expressly listed, but may include other operations or elements not expressly listed or inherent to such process, method, product, or device. Term “and/or” is used to indicate that one or all of two objects associated may be selected. For example, “A and/or B” means A, B, or A+B.

The embodiments of the present disclosure disclose a cell selection method and apparatus, user equipment and a storage medium. In the method, a signal quality of a target cell is measured, and in response to the signal quality of the target cell being less than a target threshold, cell selection is performed based on a first cell selection criteria, where a minimum access level parameter of the first cell selection criteria is greater than a minimum access level parameter of an initial cell selection criteria. When it is measured that the target cell has a poor signal quality, cell selection is performed based on the first cell selection criteria. Compared with the initial cell selection criteria, the minimum access level parameter of the cell selection criteria is increased, which increases the difficulty for the user equipment to camp on the target cell. This avoids the user equipment from camping on a cell with a poor signal quality as much as possible, thereby improving the network signal of a cell where the user equipment camps.

In order to better understand the cell selection method and apparatus, user equipment and storage medium as disclosed in the embodiments of the present disclosure, the network architecture applicable to the embodiments of the present disclosure is first described below. The method disclosed in the embodiments of the present disclosure may be applied to a 5G standalone (SA) system, and may also be applied to other communication systems. In the following, a network architecture applicable to the method as disclosed in the embodiments of the present disclosure is first introduced.

As illustrated in, a schematic diagram of a network architecture provided in the embodiments of the present disclosure is shown. This network architecture is applicable to scenarios where cell selection is required. Specifically, in such scenarios, the signal quality of a target cell is measured, and in response to the signal quality of the target cell being less than a target threshold, cell selection is performed based on a first cell selection criteria, where the minimum access level parameter of the first cell selection criteria is greater than the minimum access level parameter of the initial cell selection criteria.

A cell, also known as a cellular cell, refers to an area covered by a network device or a part of a network device (a sector antenna) in a cellular mobile communication system, within such area user equipment (UE) can communicate reliably with a base station through a wireless channel.

The network device is an entity on the network side for transmitting or receiving signals, such as gNB. User equipment is an entity on the user side for receiving or transmitting signals, such as a mobile phone. Since there are many application scenarios for base stations and UEs, it is illustrated below by taking a case where the base station is a network device as an example. As illustrated in, the network architecture includes a base station and UE (for example, UE, UEor UEshown in). The UE ineach may execute the cell selection method as described below.

The target cell is one of areas covered by the base station communicating with the UE. The UE may measure the signal quality of the target cell by interacting with the base station.

The cell selection criteria may also be referred to as S criterion.

During the cell selection, the UE uses the following two search processes.

This approach does not require any prior knowledge of a radio channel of the universal telecommunication radio access (UTRA) carrier. The UE searches all radio frequency (RF) channels in the UTRA band. On each carrier, the UE searches for the strongest cell. Then, the UE selects a suitable cell that has been pre-selected and belongs to the public land mobile network (PLMN).

This approach requires to know some stored carrier frequency information and cell parameters such as scrambling code, which are all obtained from previously measured control information elements. Once the UE finds a suitable cell that belongs to the PLMN, the UE selects this cell.

If no suitable cell is found, the initial cell selection process is initiated.

The initial cell selection criteria is as follows:

Srxlev is a reference signal received power (RSRP) value for cell selection. Squal is a reference signal receievd quality (RSRQ) value for cell selection.

Qrxlevmeas is a measured cell RSRP value, Qqualmeas is a measured cell RSRQ value, Qrxlevmin is the minimum access level parameter (i.e., the minimum RSRP value for access), Qqualmin is a minimum RSRQ value for cell access, Qrxlevminoffse is a minimum RSRP offset value for cell access, and Qqualminoffset is a minimum RSRQ offset value for cell access. Pcompensation is a difference between a maximum transmit power allowed by the network and a maximum transmit power of UE power class. Qoffsettemp is a temporary offset, and Qoffsettemp may be set to 0 or not.

In the existing protocol, the cell selection is performed according to the initial cell selection criteria, in which criteria Qrxlevmin is the minimum RSRP value for access. Qrxlevmin may be obtained from the system information sent by the network device. In the initial cell selection criteria, the minimum access level parameter Qrxlevmin is the cell minimum received level of minimum access channel requirement. If the cell selection is performed using the minimum access level parameter Qrxlevmin of the initial cell selection criteria, the UE might camp on a cell with a poor network signal, resulting in a weak signal of the UE.

In the cell selection method as provided in the embodiments of the present disclosure, when it is measured that the target cell has a poor signal quality, cell selection is performed based on the first cell selection criteria. Compared with the initial cell selection criteria, the minimum access level parameter of the cell selection criteria is increased, which increases the difficulty for the UE to camp on the target cell. This avoids the UE from camping on a cell with a poor signal quality as much as possible, thereby improving the network signal of a cell where the user equipment camps.

The cell selection method as provided in the embodiments of the present disclosure is described in detail below.

Referring to, a schematic flow chart of a cell selection method provided in the embodiments of the present disclosure is shown. As illustrated in, the cell selection method may include operationsandas follows.

At, UE measures a signal quality of a target cell.

In the embodiments of the present disclosure, the UE may communicate with a network device and obtains the signal quality of the target cell.

The UE may measure a cell quality based on multi-beam measurement, or may also derive the cell quality based on single-beam measurement (for single-beam cells, or when the UE can only see a single beam of the cell). The UE may also compare the cell qualities measured with different numbers of beams.

The signal quality of the target cell may be a reference signal received quality (RSRQ) of the target cell.

In some implementations, the UE measuring the signal quality of the target cell of operationmay include that: the UE measures the reference signal received quality RSRQ of the target cell as the signal quality of the target cell.

The reference signal received quality (RSRQ) is a measurement result on the quality of the wireless network measured by the UE. After the UE reports to the network device, the network device performs resource allocation and selects the modulation method according to the RSRQ of the UE. In 5G new radio (NR), RSRQ may be measured through synchronization signal (SS) or channel state information (CSI). The SS-RSRQ measurement result may be used for cell selection, cell reselection and mobility process, while the CSI-RSRQ measurement may only be used for mobility process.

The RSRQ of the 5G (NR) network may be measured by receiving SS reference signal or CSI reference signal. The RSRQ is measured in dB (decimalism). RSRQ measurement may be used for cell selection, reselection and mobility (handover) processes. RSRQ measurement methods: SS reference signal and CSI reference signal. The RSRQ of 5G network ranges from −43 dB to 20 dB. The RSRQ of the 5G network may be positive or negative.

At, in response to the signal quality of the target cell being less than a target threshold, the UE performs cell selection based on a first cell selection criteria, where the minimum access level parameter of the first cell selection criteria is greater than the minimum access level parameter of the initial cell selection criteria.

In the embodiments of the present disclosure, the minimum access level parameter of the initial cell selection criteria may be obtained based on system information sent to the UE. For example, the network device may send system information to the UE, and the system information may carry the minimum access level parameter of the initial cell selection criteria.

The target threshold may be set in advance, or may be determined based on a minimum required RSRQ level included in the system information sent by the network device.

The first cell selection criteria is as follows:

Qrxlevmin_1 of the first cell selection criteria is greater than Qrxlevmin of the initial cell selection criteria. The other parameters of the first cell selection criteria (parameters except Qrxlevmin_1) are the same as the other parameters of the initial cell selection criteria (parameters except Qrxlevmin).

The signal quality of the target cell being less than the target threshold indicates that the signal quality of the target cell is poor. When the signal quality of the target cell is poor, cell selection is performed based on the first cell selection criteria. Since the minimum access level parameter of the first cell selection criteria is greater than the minimum access level parameter of the initial cell selection criteria, the possibility of Srxlev>0 is reduced, and the UE has a low possibility of selecting the target cell, thereby preventing the UE from camping on a cell with a poor signal quality.

In the embodiments of the present disclosure, when it is measured that the target cell has a poor signal quality, cell selection is performed based on the first cell selection criteria. Compared with the initial cell selection criteria, the minimum access level parameter of the cell selection criteria is increased, which increases the difficulty for the UE to camp on the target cell. This avoids the UE from camping on a cell with a poor signal quality as much as possible, thereby improving the network signal of a cell where the UE camps.

Referring to, a schematic flow chart of another cell selection method provided in the embodiments of the present disclosure is shown. As illustrated in, the cell selection method may include the operations-as follows.

At, UE measures a signal quality of a target cell.

At, in response to the signal quality of the target cell being less than a target threshold, the UE performs cell selection based on a first cell selection criteria, where the minimum access level parameter of the first cell selection criteria is greater than the minimum access level parameter of the initial cell selection criteria.

For specific implementations of operationsand, reference may be made to the relevant description of operationsand, which will not be repeated here.

At, in response to the signal quality of the target cell being greater than the target threshold, the UE performs cell selection based on a second cell selection criteria, where the minimum access level parameter of the second cell selection criteria is less than the minimum access level parameter of the first cell selection criteria.

The second cell selection criteria is as follows.

Qrxlevmin_2 of the second cell selection criteria is less than Qrxlevmin_1 of the first cell selection criteria. The other parameters of the second cell selection criteria (parameters except Qrxlevmin_2) are the same as the other parameters of the first cell selection criteria (parameters except Qrxlevmin_1).